Hundreds of workers building a new power station on Teesside have staged an unofficial strike.
The dispute over pay has flared on the site at Billingham where an energy-from-waste plant is being built.
Around 250 workers, including pipe fitters and welders, walked out on Wednesday, and continued with the unofficial action on Thursday, joined by scaffolders.
The dispute is over bonus payments after work was affected by the bad weather.
A spokesman for Air Products, which will run the plant, said work was continuing despite the action, and the company was hopeful that the dispute would be resolved in the next few days.
"Foster Wheeler, the main engineering, procurement and construction management contractor at Air Products' Tees Valley renewable energy facility at Billingham, has confirmed that certain construction contractor workers have taken unofficial industrial action. The workers, mainly mechanical and piping, are expected to return to work at the site by Monday February 10.
"We believe the strike action has not been sanctioned by their trade unions nor has a ballot of the workforce been taken.
"Air Products, Foster Wheeler and the construction contractor management have held a series of talks with union representatives in recent weeks and all parties are pressing for an early resolution for the grievances submitted through the National Agreement for the Engineering Construction Industry resolution procedure.
"Work continues unaffected throughout the rest of the site. Construction of the Tees Valley Renewable Energy Facility started in 2012 and is due to enter commercial operation later this year."
County Durham & Darlington Fire Service is urging people to take extra care ahead of a Fire Brigade Union strike this evening. Resources will be reduced for five hours between 7pm to midnight on Christmas Eve.
It's part of the latest round of national strikes by the union in an ongoing dispute with the government about changes to pensions. The next strike is on New Year's Eve.
Householders are advised to check their smoke alarms, drivers are urged to stay safe by slowing down and leaving ample space behind the vehicle in front and those people spending time in the kitchen are reminded not to leave pans unattended and not to cook after drinking alcohol which can be extremely dangerous.
– Stuart Errington Deputy Chief Fire Officer, Durham and Darlington Fire and Rescue Service